Climate-driven impacts of prey abundance on the population structure of a tropical aquatic predator

In the present study we explore how annual variation in climate (late wet-season rainfall) affects population demography in a gape-limited obligate piscivorous predator, the Arafura filesnake Acrochordus arafurae in the Australian tropics. These aquatic snakes display extreme sexual dimorphism, with body sizes and relative head sizes of females much larger than those of males. Two consecutive years with low rainfall during the late wet season reduced the abundance of small but not large sized fish. Although snake residual body mass (RBM, calculated from a general linear regression of ln-transformed mass to ln-SVL) decreased after the first year with low prey availability, it was not until the second year that reduced prey abundance caused a dramatic decline in filesnake survival, and hence in population numbers. Thus, our results suggest that most snakes survived the first year of reduced prey abundance, but a successive year with low prey availability proved fatal for many animals. However, the effects of prey scarcity on RBM and survival fell disproportionately on some size classes of snakes. Medium-sized animals (large males and intermediate-sized females) were affected more dramatically than were small or large snakes. We attribute the higher survival of small snakes to their lower energy needs compared to medium-sized individuals, and the higher survival of large snakes to the continued abundance of large prey (mainly large catfish). Two successive years with low abundance of smaller sized prey thus massively modified the size-structure of the filesnake population, virtually eliminating large males and intermediate-sized females. Our field data provide a clear demonstration of the ways in which stochastic variation in climatic conditions can have dramatic effects on predator population demography, mediated via effects on prey availability.     

ACC2 gene polymorphisms,metabolic syndrome,and gene-nutrient interactions with dietary fat

Acetyl-CoA carboxylase β (ACC2) plays a key role in fatty acid synthesis and oxidation pathways. Disturbance of these pathways is associated with impaired insulin responsiveness and metabolic syndrome (MetS). Gene-nutrient interactions may affect MetS risk. This study determined the relationship between ACC2 polymorphisms (rs2075263, rs2268387, rs2284685, rs2284689, rs2300453, rs3742023, rs3742026, rs4766587, and rs6606697) and MetS risk, and whether dietary fatty acids modulate this in the LIPGENE-SU.VI.MAX study of MetS cases and matched controls (n = 1754). Minor A allele carriers of rs4766587 had increased MetS risk (OR 1.29 [CI 1.08, 1.58], P = 0.0064) compared with the GG homozygotes, which may in part be explained by their increased body mass index (BMI), abdominal obesity, and impaired insulin sensitivity (P < 0.05). MetS risk was modulated by dietary fat intake (P = 0.04 for gene-nutrient interaction), where risk conferred by the A allele was exacerbated among individuals with a high-fat intake (>35% energy) (OR 1.62 [CI 1.05, 2.50], P = 0.027), particularly a high intake (>5.5% energy) of n-6 polyunsaturated fat (PUFA) (OR 1.82 [CI 1.14, 2.94], P = 0.01; P = 0.05 for gene-nutrient interaction). Saturated and monounsaturated fat intake did not modulate MetS risk. Importantly, we replicated some of these findings in an independent cohort. In conclusion, the ACC2 rs4766587 polymorphism influences MetS risk, which was modulated by dietary fat, suggesting novel gene-nutrient interactions.     

Oxidative stress in haemostasis

The normal hemostatic mechanisms consist of a balance between hemorrhage and thrombosis that is achieved through the interaction of the blood vessels, blood platelets, the coagulation and fibrinolytic factors. The vascular endothelium sustains the balance between prevention and stimulation of platelet activation, thrombogenesis and fibrinolysis and between vasoconstriction and vasodilatation. Endothelial dysfunction associated with different cardiovascular diseases is related to the local formation of reactive oxygen/nitrogen species, mainly peroxynitrite that is produced in a rapid reaction between nitric oxide and superoxide anion. Reactive oxygen/nitrogen species induce changes in the structure and function in hemostatic elements. Proteins and lipids are major initial targets in endothelial cells, blood platelets and plasma. Reaction of reactive oxygen species and nitrogen species, including peroxynitrite, with cellular proteins can lead to nitration of aromatic amino acid residues, oxidation of thiol groups and conversion of some amino acid residues into carbonyl derivative. Oxidative/nitrative modifications of platelet proteins may induce changes of their signaling and haemostatic function (activation). Peroxynitrite also causes oxidation and nitration of fibrinogen--a key protein in coagulation cascade and plasminogen (the main protein of fibrinolysisprocess) changing their hemostatic functions. Oxidative/nitrative modifications of different components of haemostasis system have been observed in several cardiovascular diseases.     

Anti-inflammatory plasma cytokines in children and adolescents with Down syndrome

Cytokines participate in many physiological processes including the regulation of immune and inflammatory responses. Production of some important cytokines in children with Down syndrome (DS) is depressed or increased. In this study we analysed the selected anti- inflammatory cytokines: interleukin-4 (IL-4), interleukin-10 (IL-10), interleukin-13 (IL-13) in plasma of children and adolescents with DS. The study group consisted of 20 patients with Down syndrome and 33 healthy subjects at the age of 5-17 years. Levels of: IL-4, IL-10 and IL-13 in plasma samples were determined by specific enzyme- linked immunosorbent assay (ELISA) techniques according to manufacturer's instructions. IL-4 was detectable in 25% subjects with Down syndrome and in 28.6% healthy subjects. IL-13 was detectable in 15% patients with Down syndrome and in 15.2% healthy subjects, respectively. IL-10 was detectable in 1 of 20 patients with Down syndrome and in 2 of 33 healthy subjects only. No significant correlations between measurable cytokine levels and age and gender were found. No significant increased concentration of selected anti- inflammatory cytokines were detected.     

Regulation of cell survival and death during Flavivirus infections

Flaviviruses, ss(+) RNA viruses, include many of mankind's most important pathogens. Their pathogenicity derives from their ability to infect many types of cells including neurons, to replicate, and eventually to kill the cells. Flaviviruses can activate tumor necrosis factor α and both intrinsic(Bax-mediated) and extrinsic pathways to apoptosis. Thus they can use many approaches for activating these pathways. Infection can lead to necrosis if viral load is extremely high or to other types of cell death if routes to apoptosis are blocked. Dengue and Japanese Encephalitis Virus can also activate autophagy. In this case the autophagy temporarily spares the infected cell, allowing a longer period of reproduction for the virus, and the autophagy further protects the cell against other stresses such as those caused by reactive oxygen species. Several of the viral proteins have been shown to induce apoptosis or autophagy on their own, independent of the presence of other viral proteins. Given the versatility of these viruses to adapt to and manipulate the metabolism, and thus to control the survival of, the infected cells, we need to understand much better how the specific viral proteins affect the pathways to apoptosis and autophagy. Only in this manner will we be able to minimize the pathology that they cause.     

Significance of Stereochemistry of 3′-Terminal Phosphorothioate-modified Primer in DNA Polymerase-mediated Chain Extension

Influence of stereochemistry of the 3′-terminal phosphorothioate (PS)-modified primers was studied in a single base extension (SBE) assay to evaluate any improvements in specificity. SBE reactions were catalyzed by members of the high fidelity Pfu family of DNA polymerases with (exo+) or without (exo−) 3′ → 5′ exonucleolytic activity. The diastereomerically pure PS-labeled primers used in these studies were obtained either by the stereospecific chemical synthesis invented in our laboratory or by the more conventional ion-exchange chromatographic method for separation of a mixture of diastereomers (R_P and S_P). When the SBE reaction was performed in the presence of mispaired 2′-deoxyribonucleoside triphosphates (dNTPs), the “racemic” 3′-phosphorothioate primer mixture resulted in a lower level of 3′ → 5′ exonuclease-mediated cleavage products in comparison to the SBE reactions carried out with the corresponding unmodified primer. When the diastereomerically pure R_P 3′-phosphorothioate primer was examined, the results were largely the same as for the racemic 3′-phosphorothioate primer mixture. In contrast, a 3′-PS primer of S_P configuration displayed significantly improved performance in the SBE reaction. This included the lack of 3′ → 5′ proofreading products, less mispriming, and improved yield of incorporation of the correct nucleotide.     

Aromatase expression in testes of XY, YY, and XX rainbow trout (Oncorhynchus mykiss).

The main goal of the present study was to show whether testicular cells of rainbow trout (Oncorhynchus mykiss Walbaum) either hormonally manipulated (XX males) or produced by using gamma irradiation and pressure shock (YY males, "supermales") are able to aromatize androgens into estrogens compared with the control (XY males). The expression of aromatase gene at the level of the protein and its presence in testicular tissue was investigated by means of immunohistochemistry and Western blot analysis, respectively. The positive staining for aromatase was detected in testicular cells of all trout and in efferent duct cells of XY and YY males. However, the staining intensity varied among particular trout, being strong in YY males, moderate in XY males, and weak in XX trout. It was confirmed by quantitative image analysis in which the staining intensity was expressed as relative optical density (ROD) of diaminobenzidine deposits. Significant differences were found between XY and YY trout ((**)p<0.01) and XY and XX trout ((*)p<0.05). Such differences could reflect various levels of estrogens, possibly dependent on the genetic background of the trout studied. It seems likely that differential expression of the enzyme, especially that of weak or strong intensity, causes some alterations in testicular morphology of homogametic trout. Additionally, the results indicate that an imbalance in sex hormone biosynthesis may provoke the functional alterations in testes of YY males, and, in consequence, negatively affect the fertility of "supermales".     

Neuroendocrine tumors of the small intestine and the appendix - management guidelines (recommended by The Polish Network of Neuroendocrine Tumors)

Polish recommendations regarding management of patients suffering from neuroendocrine tumors of small intestine and appendix are presented. Small intestine, especially ileum represent most common origin of these tumors. Majority of them are well differentiated and grow slowly. Rarely, they are less differentiated with fast growth and poor prognosis. Symptoms are atypical, diagnosis could be often accidental. In 4-10% of patients typical symptoms of carcinoid syndrome are present. Chromogranin A is useful in the laboratory diagnostics, and urinary excretion of 5-hydroxyindoloacetic acid is helpful for the diagnostics and monitoring of the disease. Histopathological diagnostics was extensively described. Ultrasound, colonoscopy, capsule endoscopy, baloon enteroscopy, computed tomography, magnetic resonance and somatostatin analogs scintigraphy could be used for the visualization. The treatment of choice in the neuroendocrine tumors of small intestine and appendix is radical or palliative surgery, if possible using endoscopy. Pharmacotherapy consists of biotherapy and chemotherapy. The crucial in biotherapy is somatostatin analogs application, possible in symptomatic treatment of hormonally functioning tumors. This is treatment of choice in carcinoid crisis. Interferon alfa could be applied because of the same indications as somatostatin analogs, except for carcinoid crisis. Chemotherapy is less successful in disseminated or locally advanced intestinal neuroendocrine tumors, so radioisotope therapy should be considered in each case of unresectable tumor.